Chemical thermal storage device

ABSTRACT

A chemical thermal storage device includes a reactor that is disposed around a heat exchanger and contains a thermal storage material that generates heat upon chemical reaction with NH3 and desorbs NH3 upon reception of waste heat, an adsorber containing an adsorption material capable of retention and desorption of NH3 through physical adsorption, a solenoid valve that is provided between the reactor and the adsorber and opens and closes a flow channel between both, and a safety valve that is provided in parallel to the solenoid valve between the reactor and the adsorber and mechanically opens when a pressure in the reactor reaches a preset valve-opening setting pressure. The safety valve has a check valve function to shut off a flow of NH3 from the adsorber to the reactor.

TECHNICAL FIELD

The present invention relates to a chemical thermal storage device whichheats a heating object, for example, provided in an exhaust system of anengine or the like.

BACKGROUND ART

As a conventional chemical thermal storage device, as disclosed inPatent Literature 1 by way of example, there is known a non-recoverytype heating device which heats engine elemental components. A chemicalthermal storage device disclosed in Patent Literature 1 includes anammonia adsorber having an ammonia adsorption material capable offixation and desorption of ammonia (NH₃) as a chemical reaction medium,a chemical thermal storage reactor that is connected to the ammoniaadsorber via a pipe and has a chemical thermal storage material thatgenerates heat upon chemical reaction with NH₃ and desorbs NH₃ withexcess heat from a heat source, and an opening and closing valveprovided on the pipe.

In starting the engine, by releasing the opening and closing valve, NH₃desorbed from the ammonia adsorption material of the ammonia adsorber issupplied to the chemical thermal storage reactor via the pipe. Then, thechemical thermal storage material generates heat through chemicalreaction between NH₃ and the chemical thermal storage material, and theengine elemental components are heated by the heat. After the warming upof the engine, NH₃ is desorbed from the chemical thermal storagematerial with excess heat of the engine elemental components. Then, thisNH₃ is fixed again (recovered) into the ammonia adsorption material viathe pipe. After that, the opening and closing valve is closed.

CITATION LISt Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2013-72558

SUMMARY OF INVENTION Technical Problem

However, the following problem is in the aforementioned conventionalart. That is, in recovering NH₃, the chemical thermal storage reactor(hereinafter simply a reactor) becomes in a high temperature state. Whenstopping the engine in this state, the opening and closing valve isclosed in the case where the opening and closing valve is a solenoidvalve. In such a state, since NH₃ cannot be returned from the reactor tothe ammonia adsorber (hereinafter simply an adsorber), the inside of thereactor is filled with NH₃ and the inside of the reactor becomes in anabnormal over-pressurized state. In this stage, in order not to allowthe reactor to burst, it is needed to make the rigidity of the reactorsufficiently high, which causes a physical constitution and a weight ofthe reactor to increase more than needed.

Moreover, in order to cause the chemical thermal storage material of thereactor to generate heat at high temperature, a pressure not less thanseveral arms is needed. Due to this, for the adsorber, rigidity whichcan be resistant to this pressure is needed. Now, the pressure in theadsorber varies depending on the outside air temperature. Specifically,when the outside air temperature becomes high, the temperature of theadsorber becomes high and the pressure in the adsorber becomes high.Here, in the case where the opening and closing valve is closed, sinceeven when the outside air temperature rises and the adsorber becomes ina high temperature state, NH₃ cannot move from the adsorber to thereactor, the inside of the adsorber is filled with NH₃ and the inside ofthe adsorber becomes in an abnormal over-pressurized state. Accordingly,when designing the adsorber with the variation of the outside airtemperature taken into consideration, it is needed to make the rigidityof the adsorber sufficiently high, which causes a physical constitutionand a weight of the adsorber to increase more than needed.

An object of the present invention is to provide a chemical thermalstorage device capable of preventing the inside of a reactor or anadsorber from becoming in an abnormal over-pressurized state.

Solution to Problem

There is provided a chemical thermal storage device according to thepresent invention which heats a heating object, the device comprising: areactor having a thermal storage material that generates heat uponchemical reaction with a gaseous reaction medium; an adsorber having anadsorption material that adsorbs the reaction medium; an opening andclosing valve that is provided between the reactor and the adsorber, andopens and closes a flow channel between the reactor and the adsorber;and communication part that causes the reactor and the adsorber tocommunicate with each other when an internal pressure of at least one ofthe reactor and the adsorber becomes not less than a predeterminedvalue.

In such a chemical thermal storage device according to the presentinvention, since even in the state where the opening and closing valveprovided between the reactor and the adsorber is closed, the reactor andthe adsorber communicates with each other when the internal pressure ofat least one of the reactor and the adsorber becomes not less than apredetermined value, the reaction medium becomes to move between thereactor and the adsorber. In this way, the inside of the reactor or theadsorber can be prevented from becoming in an abnormal over-pressurizedstate.

The communication part may also be provided between the reactor and theadsorber, and may also have at least one of a first valve that openswhen the internal pressure of the reactor reaches a first valve-openingsetting pressure that is preset and a second valve that opens when theinternal pressure of the adsorber reaches a second valve-opening settingpressure that is preset. In such a configuration, when the internalpressure of the reactor reaches the first valve-opening setting pressureof the first valve, the first valve opens and the reaction mediumbecomes to move from the reactor to the adsorber. Moreover, when theinternal pressure of the adsorber reaches the second valve-openingsetting pressure of the second valve, the second valve opens and thereaction medium becomes to move from the adsorber to the reactor. Inthis way, even when not using a sensor that detects the internalpressure of the reactor or the adsorber, the inside of the reactor orthe adsorber can be securely prevented from becoming in an abnormalover-pressurized state.

In this stage, the first valve may also include a check valve functionto shut off a flow of the reaction medium from the adsorber to thereactor, and the second valve may also include a check valve function toshut off a flow of the reaction medium from the reactor to the adsorber.In this case, even when the internal pressure of the adsorber reachesthe first valve-opening setting pressure of the first valve, thereaction medium does not move from the adsorber to the reactor.Moreover, even when the internal pressure of the reactor reaches thesecond valve-opening setting pressure of the second valve, the reactionmedium does not move from the reactor to the adsorber.

Moreover, the first valve and the second valve may also be providedbetween the reactor and the adsorber, and the second valve-openingsetting pressure may also be larger than the first valve-opening settingpressure. In this case, the second valve can be suppressed from openingfor the reaction medium to move from the adsorber to the reactor in thenormal state where the internal pressure of the adsorber is relativelyhigh.

Furthermore, any one of the first valve and the second valve may alsoconstitute one unit along with the opening and closing valve. In thiscase, since the number of valve units to be used can be a minimumrequirement, which is advantageous in view of costs.

Moreover, the communication part may also further have a bypass passageprovided in parallel to the opening and closing valve, and at least oneof the first valve and the second valve may also be provided on thebypass passage. In this case, structures of the opening and closingvalve, the first valve and the second valve become simple.

Moreover, the communication part may also have detector that detects theinternal pressure of at least one of the reactor and the adsorber, andcontroller that performs control so as to open the opening and closingvalve when it is detected by the detector that the internal pressure ofat least one of the reactor and the adsorber is not less than thepredetermined value. In such a configuration, when the internal pressureof the reactor becomes not less than the predetermined value, theopening and closing valve opens and the reaction medium becomes to movefrom the reactor to the adsorber. Moreover, when the internal pressureof the adsorber becomes not less than the predeteiinined value, theopening and closing valve opens and the reaction medium becomes to movefrom the adsorber to the reactor. In this way, while the number ofvalves to be used is a minimum requirement, the inside of the reactor orthe adsorber can be securely prevented from becoming in an abnormalover-pressurized state.

Furthermore, the chemical thermal storage device may also furthercomprise a relief valve that opens when the internal pressure of atleast one of the reactor and the adsorber reaches a predetermined reliefsetting value. In this case, even when the internal pressure of at leastone of the reactor and the adsorber becomes high to an extent to whichthe communication part cannot handle it, when the internal pressure ofat least one of the reactor and the adsorber reaches the relief settingvalue, the relief valve opens and the reaction medium becomes to bedischarged from at least one of the reactor and the adsorber. In thisway, the inside of the reactor or the adsorber can be further preventedfrom becoming in an abnormal over-pressurized state.

In this stage, the heating object may also be provided in an exhaustsystem of an engine, and the relief valve may also be provided betweenthe exhaust system and at least one of the reactor and the adsorber. Inthis case, when the internal pressure of at least one of the reactor andthe adsorber reaches the relief setting value, the relief valve opensand the reaction medium is to be discharged from at least one of thereactor and the adsorber to the exhaust system.

Advantageous Effects of Invention

According to the present invention, the inside of the reactor or theadsorber can be prevented from becoming in an abnormal over-pressurizedstate. Therefore, it is not needed to make a physical constitution and aweight of the reactor or the adsorber larger than needed in order not toallow the reactor or the adsorber to burst, and costs can be downsized.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram illustrating an exhaustpurification system including a first embodiment of a chemical thermalstorage device according to the present invention.

FIG. 2 is a conceptual diagram illustrating operation of the chemicalthermal storage device illustrated in FIG. 1.

FIG. 3 is a schematic configuration diagram illustrating an exhaustpurification system including a second embodiment of the chemicalthermal storage device according to the present invention.

FIG. 4 is a conceptual diagram illustrating operation of the chemicalthermal storage device illustrated in FIG. 3.

FIG. 5 is a schematic configuration diagram illustrating an exhaustpurification system including a third embodiment of the chemical thermalstorage device according to the present invention.

FIG. 6 is a conceptual diagram illustrating operation of the chemicalthermal storage device illustrated in FIG. 5.

FIG. 7 is a schematic configuration diagram illustrating an exhaustpurification system including a fourth embodiment of the chemicalthermal storage device according to the present invention.

FIG. 8 is a conceptual diagram illustrating operation of the chemicalthermal storage device illustrated in FIG. 7.

FIG. 9 is a schematic configuration diagram illustrating an exhaustpurification system including a fifth embodiment of the chemical thermalstorage device according to the present invention.

FIG. 10 is a conceptual diagram illustrating operation of the chemicalthermal storage device illustrated in FIG. 9.

FIG. 11 is a schematic configuration diagram illustrating an exhaustpurification system including a sixth embodiment of the chemical thermalstorage device according to the present invention.

FIG. 12 is a flowchart illustrating details of solenoid valve controlprocessing procedures executed by the controller illustrated in FIG. 11.

FIG. 13 is a conceptual diagram illustrating operation of the chemicalthermal storage device illustrated in FIG. 11.

DESCRIPTION OF EMBODIMENTS

Hereafter, preferable embodiments of a chemical thermal storage deviceaccording to the present invention are described in detail withreference to the drawings. Notably, the same or equivalent elements inthe drawings are given the same signs and their duplicated descriptionis omitted.

FIG. 1 is a schematic configuration diagram illustrating an exhaustpurification system including a first embodiment of the chemical thermalstorage device according to the present invention. In the figure, anexhaust purification system 1 is provided in an exhaust system of adiesel engine 2 of a vehicle (hereinafter referred to simply as engine2), and is a system that purifies harmful substances (environmentalpollutants) contained in exhaust gas discharged from the engine 2.

The exhaust purification system 1 includes a heat exchanger 4, anoxidation catalyst (DOC: Diesel Oxidation Catalyst) 5, a diesel exhaustparticulate removal filter (DPF: Diesel Particulate Filter) 6, aselective reduction catalyst (SCR: Selective Catalytic Reduction) 7 andan oxidation catalyst (ASC: Ammonia Slip Catalyst) 8, which are arrangedin the middle of an exhaust passage 3 (exhaust system) connected to theengine 2 sequentially from the upstream side toward the downstream side.

The heat exchanger 4 is a device that performs transfer of heat betweenthe exhaust gas from the engine 2 and a reactor 11 mentioned later, andforms a honeycomb structure. Notably, the heat exchanger 4 can use aknown heat exchange structure, which is not limited to the honeycombstructure. The oxidation catalyst 5 is a catalyst that oxidizes HC(hydrocarbon), CO and the like contained in the exhaust gas and purifiesthe exhaust gas. The DPF 6 is a filter that collects and removesparticulate matter (PM: Particulate Matter) contained in the exhaustgas. The SCR 7 is a catalyst that reduces NO_(x) contained in theexhaust gas with urea or ammonia (NH₃) and purifies the exhaust gas. Theoxidation catalyst 8 is a catalyst that oxidizes NH₃ that has passedthrough the SCR 7 and flowed to the downstream side of the SCR 7.

Moreover, the exhaust purification system 1 includes the chemicalthermal storage device 10 of the present embodiment. The chemicalthermal storage device 10 is a device that heats the heat exchanger 4without energy by normally storing heat of the exhaust gas (waste heat)and using the waste heat when needed. The chemical thermal storagedevice 10 includes the reactor 11 disposed around the heat exchanger 4and an adsorber 12 disposed separate from the heat exchanger 4.

The reactor 11 contains a thermal storage material 13 that generatesheat for heating the heat exchanger 4 upon chemical reaction with NH₃which is a gaseous reaction medium and that desorbs NH₃ upon receptionof the waste heat. As the thermal storage material 13, a material havinga constitution which is MX_(a) which is a halide is used. Herein, M isan alkali earth metal such as Mg, Ca and Sr, or a transition metal suchas Cr, Mn, Fe, Co, Ni, Cu and Zn. X is a halogen atom such as Cl, Br andI. a is 2 to 3.

The adsorber 12 contains an adsorption material 14 capable of retentionand desorption of NH₃ through physical adsorption. As the adsorptionmaterial 14, activated carbon, carbon black, mesoporous carbon,nanocarbon or the like is used. In the adsorber 12, NH₃ can be stored bycausing the adsorption material 14 to perform physical adsorption ofNH₃.

The reactor 11 and the adsorber 12 are connected to each other via amain pipe 15. On the main pipe 15, a solenoid valve 16 which is anopening and closing valve that opens and closes a flow channel betweenthe reactor 11 and the adsorber 12 is provided. The solenoid valve 16 iscontrolled by a controller (not shown).

To the main pipe 15, a bypass pipe 17 (bypass passage) is connected. Onthe bypass pipe 17, a mechanical safety valve 18 is provided in parallelto the solenoid valve 16. The safety valve 18 is a separate unit fromthe solenoid valve 16. The safety valve 18 is a valve (first valve) thatmechanically opens when the pressure in the reactor 11 reaches avalve-opening setting pressure (first valve-opening setting pressure).The valve-opening setting pressure is preset with a spring (not shown)provided in the safety valve 18.

The safety valve 18 has a check valve function to shut off a flow of NH₃from the adsorber 12 to the reactor 11. Accordingly, although when thepressure in the reactor 11 reaches the valve-opening setting pressure,NH₃ moves from the reactor 11 to the adsorber 12 by the safety valve 18opening, even when the pressure in the adsorber 12 reaches thevalve-opening setting pressure, NH₃ does not move from the adsorber 12to the reactor 11.

Herein, the safety valve 18 constitutes communication part that causesthe reactor 11 and the adsorber 12 to communicate with each other whenthe internal pressure of at least one of the reactor 11 and the adsorber12 becomes not less than a predetermined value.

In the chemical thermal storage device 10 as above, when the temperatureof the exhaust gas from the engine 2 is low, NH₃ is supplied from theadsorber 12 to the reactor 11 via the main pipe 15 by the solenoid valve16 opening. When the thermal storage material 13 (for example, MgBr₂) ofthe reactor 11 and NH₃ undergo chemical reaction to result in chemicaladsorption (coordinate bonding), heat is generated from the thermalstorage material 13. In other words, a reaction (exothermic reaction)from the left side to the right side in the following reaction formula(A) takes place. Then, the heat exchanger 4 is heated by the heatgenerated in the reactor 11.

MgBr₂+xNH₃

Mg(NH₃)_(x)Br₂+heat   (A)

On the other hand, when the temperature of the exhaust gas from theengine 2 becomes high, the thermal storage material 13 and NH₃ areseparated from each other by waste heat given to the thermal storagematerial 13 of the reactor 11. In other words, a reaction (regenerationreaction) from the right side to the left side in the above reactionformula (A) takes place. Then, NH₃ desorbed from the thermal storagematerial 13 returns to the adsorber 12 via the main pipe 15 andundergoes physical adsorption (is recovered) in the adsorption material14 of the adsorber 12.

Here, when stopping the engine 2 in recovering NH₃ with waste heat,since electricity becomes not to be supplied to the solenoid valve 16,the solenoid valve 16 closes. Then, as illustrated in FIG. 2, the insideof the reactor 11 is filled with high temperature NH₃ gas and thepressure in the reactor 11 steeply rises. In this stage, since when thepressure in the reactor 11 reaches the valve-opening setting pressure ofthe safety valve 18, the safety valve 18 opens, NH₃ in the reactor 11becomes to move to the adsorber 12 through the bypass pipe 17. In thisway, the inside of the reactor 11 is not abnormally over-pressurized.

As above, according to the present embodiment, even when the pressure inthe reactor 11 steeply rises due to the solenoid valve 16 closing inrecovering NH₃, since the safety valve 18 operates, the inside of thereactor 11 can be prevented from being abnormally over-pressurized.Accordingly, since it is not needed to make the reactor 11 into anunnecessarily tough structure so as not to allow the reactor 11 toburst, a physical constitution and a weight of the reactor 11 can besuppressed from increasing and costs can be downsized.

FIG. 3 is a schematic configuration diagram illustrating an exhaustpurification system including a second embodiment of the chemicalthermal storage device according to the present invention. In thefigure, the chemical thermal storage device 10 of the present embodimentincludes a safety valve unit 20 in place of the safety valve 18 in theaforementioned first embodiment. The safety valve unit 20 has amechanical safety valve 21 (first valve) and a mechanical safety valve22 (second valve) that is provided in parallel to this safety valve 21.

The safety valve 21 is a valve (first valve) that mechanically openswhen the pressure in the reactor 11 reaches a valve-opening settingpressure for the reactor (first valve-opening setting pressure). Thevalve-opening setting pressure for the reactor is preset with a spring(not shown) provided in the safety valve 21. The safety valve 21 has acheck valve function to shut off a flow of NH₃ from the adsorber 12 tothe reactor 11.

The safety valve 22 is a valve (second valve) that mechanically openswhen the pressure in the adsorber 12 reaches a valve-opening settingpressure for the adsorber (second valve-opening setting pressure). Thevalve-opening setting pressure for the adsorber is preset with a spring(not shown) provided in the safety valve 22. The safety valve 22 has acheck valve function to shut off a flow of NH₃ from the reactor 11 tothe adsorber 12.

In the normal state, the pressure in the adsorber 12 is higher than thepressure in the reactor 11. Due to this, the valve-opening settingpressure, for the adsorber, of the safety valve 22 is set to be higherthan the valve-opening setting pressure, for the reactor, of the safetyvalve 21.

Herein, the safety valves 21 and 22 constitute communication part thatcauses the reactor 11 and the adsorber 12 to communicate with each otherwhen the internal pressure of at least one of the reactor 11 and theadsorber 12 becomes not less than a predetermined value.

When stopping the engine 2 in recovering NH₃, since the solenoid valve16 closes as mentioned above, as illustrated in FIG. 4(a), the inside ofthe reactor 11 is filled with high temperature NH₃ gas and the pressurein the reactor 11 steeply rises. In this stage, since when the pressurein the reactor 11 reaches the valve-opening setting pressure, for thereactor, of the safety valve 21, the safety valve 21 opens, NH₃ in thereactor 11 becomes to move to the adsorber 12 through the bypass pipe17. In this way, the inside of the reactor 11 is not abnormallyover-pressurized.

Since when heat is given to the adsorber 12 due to the outside airtemperature rising and the adsorber 12 becomes in a high temperaturestate while the engine 2 is stopped, the solenoid valve 16 is closed, asillustrated in FIG. 4(b), the pressure in the adsorber 12 steeply riseswith high temperature NH₃ gas in the adsorber 12. In this stage, sincewhen the pressure in the adsorber 12 reaches the valve-opening settingpressure, for the adsorber, of the safety valve 22, the safety valve 22opens, NH₃ in the adsorber 12 becomes to move to the reactor 11 throughthe bypass pipe 17. In this way, the inside of the adsorber 12 is notabnormally over-pressurized.

Accordingly, in addition to that it is not needed to make the reactor 11into an unnecessarily tough structure so as not to allow the reactor 11to burst, it is not needed to make the adsorber 12 into an unnecessarilytough structure so as not to allow the adsorber 12 to burst. Due tothis, physical constitutions and weights of the reactor 11 and theadsorber 12 can be suppressed from increasing and costs can be furtherdownsized.

Moreover, the valve-opening setting pressure, for the adsorber, of thesafety valve 22 is higher than the valve-opening setting pressure, forthe reactor, of the safety valve 21. Due to this, even when the pressurein the adsorber 12 becomes high, the safety valve 22 does notimmediately open and erroneous movement of NH₃ from the adsorber 12 tothe reactor 11 can be suppressed from occurring. Moreover, since thevalve-opening setting pressure, for the reactor, of the safety valve 21is lower than the valve-opening setting pressure, for the adsorber, ofthe safety valve 22, movement of NH₃ from the reactor 11 to the adsorber12 is facilitated and recovery of NH₃ can be promoted.

FIG. 5 is a schematic configuration diagram illustrating an exhaustpurification system including a third embodiment of the chemical thermalstorage device according to the present invention. In the figure, thechemical thermal storage device 10 of the present embodiment includes arelief valve 30 in addition to the aforementioned configuration in thesecond embodiment.

The relief valve 30 is provided on a pipe 31 that connects the reactor11 and the exhaust passage 3. One end of the pipe 31 is connected to anexhaust pipe 32 that joins the heat exchanger 4 and the oxidationcatalyst 5 on the exhaust passage 3.

The relief valve 30 is a valve that mechanically opens when the pressurein the reactor 11 reaches a relief setting value. The relief settingvalue is preset with a spring (not shown) provided in the relief valve30. The relief setting value is set to be higher than the valve-openingsetting pressure, for the reactor, of the safety valve 21. The reliefvalve 30 has a check valve function to shut off a flow of gas from theexhaust pipe 32 to the reactor 11.

Since when both the reactor 11 and the adsorber 12 becomes in hightemperature states while the engine 2 is stopped, the solenoid valve 16is closed, as illustrated in FIG. 6, the pressures in the reactor 11 andthe adsorber 12 steeply rise with high temperature NH₃ gas in thereactor 11 and the adsorber 12. In this stage, when the pressure in thereactor 11 reaches the valve-opening setting pressure, for the reactor,of the safety valve 21, the safety valve 21 opens, and when the pressurein the adsorber 12 reaches the valve-opening setting pressure, for theadsorber, of the safety valve 22, the safety valve 22 opens.Nevertheless, the inside of the reactor 11 and the inside of theadsorber 12 are still in the state of being over-pressurized by the NH₃gas.

Since when the pressure in the reactor 11 reaches the relief settingpressure of the relief valve 30, the relief valve 30 opens, NH₃ in thereactor 11 becomes to be released through the pipe 31 to the exhaustpipe 32 in the previous stage of the oxidation catalyst 5. Then, NH₃released to the exhaust pipe 32 is oxidized by the oxidation catalyst 5to be NO_(x).

In this way, even when a situation that cannot be handled with thesafety valves 21 and 22 occurs due to each of the pressures in thereactor 11 and the adsorber 12 steeply rising, NH₃ is released from theinside of the reactor 11 to the exhaust pipe 32 by the operation of therelief valve 30. In this way, the inside of the reactor 11 and theinside of the adsorber 12 can be prevented from being abnormallyover-pressurized.

Notably, in the present embodiment, while the configuration is made torelease NH₃ in the reactor 11 to the exhaust pipe 32 in the previousstage of the oxidation catalyst 5, the release destination of NH₃ is notspecially limited to the exhaust pipe 32 but may also be an exhaust pipein the previous stage of any of the heat exchanger 4, the diesel exhaustparticulate removal filter 6, the selective reduction catalyst 7 and theoxidation catalyst 8, or the like.

Moreover, in the present embodiment, while the configuration is made toprovide the relief valve 30 which opens when the pressure in the reactor11 reaches the relief setting value between the reactor 11 and theexhaust passage 3, the configuration may also be made to provide arelief valve that opens when the pressure in the adsorber 12 reaches therelief setting value between the adsorber 12 and the exhaust passage 3,or the configuration may also be made to provide a relief valve thatopens when the pressure in the reactor 11 or the adsorber 12 reaches therelief setting value on a passage that joins the reactor 11 and theadsorber 12.

FIG. 7 is a schematic configuration diagram illustrating an exhaustpurification system including a fourth embodiment of the chemicalthermal storage device according to the present invention. In thefigure, the chemical thermal storage device 10 of the present embodimentincludes a solenoid valve unit 40 in place of the solenoid valve 16 andthe safety valve 18 in the aforementioned first embodiment.

The solenoid valve unit 40 includes the check valve 42 with respect tothe solenoid valve 41 as an opening and closing valve which is the mainpart. The solenoid valve 41 and the check valve 42 constitute one unit.In other words, the solenoid valve unit 40 is the solenoid valve 41equipped with the check valve 42. The solenoid valve unit 40 iscontrolled by a controller (not shown).

The solenoid valve 41 is a valve that opens and closes the flow channelbetween the reactor 11 and the adsorber 12. The check valve 42 is avalve (first valve) that mechanically opens when the pressure in thereactor 11 reaches a valve-opening setting pressure (first valve-openingsetting pressure) and that shuts off a flow of NH₃ from the adsorber 12to the reactor 11. The valve-opening setting pressure is preset with aspring (not shown) provided in the solenoid valve unit 40.

Herein, the check valve 42 constitutes communication part that causesthe reactor 11 and the adsorber 12 to communicate with each other whenthe internal pressure of at least one of the reactor 11 and the adsorber12 becomes not less than a predetermined value.

When stopping the engine 2 in recovering NH₃, the solenoid valve unit 40closes based on operation of the solenoid valve 41. Then, as illustratedin FIG. 8, the inside of the reactor 11 is filled with high temperatureNH₃ gas and the pressure in the reactor 11 steeply rises. In this stage,since when the pressure in the reactor 11 reaches the valve-openingsetting pressure of the solenoid valve unit 40, the solenoid valve unit40 opens based on operation of the check valve 42, NH₃ in the reactor 11becomes to move to the adsorber 12 through the main pipe 15. In thisway, the over-pressurized state in the reactor 11 can be relieved.

FIG. 9 is a schematic configuration diagram illustrating an exhaustpurification system including a fifth embodiment of the chemical thermalstorage device according to the present invention. In the figure, thechemical thermal storage device 10 of the present embodiment includes amechanical safety valve 45 in addition to the aforementionedconfiguration in the fourth embodiment.

The safety valve 45 is provided on a bypass pipe 46 (bypass passage)connected to the main pipe 15 in parallel to the solenoid valve unit 40.The safety valve 45 is a valve (second valve) that mechanically openswhen the pressure in the adsorber 12 reaches a valve-opening settingpressure for the adsorber (second valve-opening setting pressure). Thevalve-opening setting pressure for the adsorber is preset with a spring(not shown) provided in the safety valve 45. The valve-opening settingpressure, for the adsorber, of the safety valve 45 is set to be higherthan the valve-opening setting pressure (first valve-opening settingpressure) of the solenoid valve unit 40. Moreover, the safety valve 45has a check valve function to shut off a flow of NH₃ from the reactor 11to the adsorber 12.

Herein, the check valve 42 and the safety valve 45 constitutecommunication part that causes the reactor 11 and the adsorber 12 tocommunicate with each other when the internal pressure of at least oneof the reactor 11 and the adsorber 12 becomes not less than apredetermined value.

Since when heat is given to the adsorber 12 due to the outside 1.5 airtemperature rising and the adsorber 12 becomes in a high temperaturestate while the engine 2 is stopped, the solenoid valve unit 40 isclosed, as illustrated in FIG. 10, the pressure in the adsorber 12steeply rises with high temperature NH₃ gas in the adsorber 12. In thisstage, since when the pressure in the adsorber 12 reaches thevalve-opening setting pressure, for the adsorber, of the safety valve45, the safety valve 45 opens, NH₃ in the adsorber 12 becomes to move tothe reactor 11 through the bypass pipe 46. In this way, theover-pressurized state in the adsorber 12 can be relieved.

FIG. 11 is a schematic configuration diagram illustrating an exhaustpurification system including a sixth embodiment of the chemical thermalstorage device according to the present invention. In the figure, whilethe chemical thermal storage device 10 of the present embodiment has themain pipe 15 and the solenoid valve 16 in the aforementioned firstembodiment, it does not have the bypass pipe 17 and the safety valve 18therein.

The chemical thermal storage device 10 includes a pressure sensor 50(detector) that detects the pressure in the adsorber 12 and a controller51 (controller) connected to this pressure sensor 50. The controller 51controls the solenoid valve 16 based on a detection value of thepressure sensor 50.

FIG. 12 is a flowchart illustrating details of solenoid valve controlprocessing procedures executed by the controller 51. The processing isexecuted during a period except the occasion of the exothermic reactionand the occasion of the regeneration reaction. Notably, the solenoidvalve 16 is in the closed state during the period except the occasion ofthe exothermic reaction and the occasion of the regeneration reaction.

In FIG. 12, first, the detection value of the pressure sensor 50 isinputted (procedure S101) and it is determined whether the pressure, inthe adsorber 12, detected by the pressure sensor 50 (adsorber pressure)is lower than a setting pressure (procedure S102). The setting pressureis preset based on an experiment or the like.

When the pressure in the adsorber 12 is lower than the setting pressure,control is performed so as to close the solenoid valve 16 (procedureS103), returning to procedure S101. When the pressure in the adsorber 12is not less than the setting pressure, control is performed so as toopen the solenoid valve 16 (procedure S104), returning to procedureS101.

Herein, the pressure sensor 50 and the controller 51 constitutecommunication part that causes the reactor 11 and the adsorber 12 tocommunicate with each other when the internal pressure of at least oneof the reactor 11 and the adsorber 12 becomes not less than apredetermined value.

Even in a state where the engine 2 does not stop, the solenoid valve 16is closed during the period except the occasion of the exothermicreaction and the occasion of the regeneration reaction. Due to this,when heat is given to the adsorber 12 due to the outside air temperaturerising and the adsorber 12 becomes in a high temperature state, asillustrated in FIG. 13, the pressure in the adsorber 12 steeply riseswith high temperature NH₃ gas in the adsorber 12. In this stage, sincewhen the pressure in the adsorber 12 reaches the setting pressure, thesolenoid valve 16 opens, NH₃ in the adsorber 12 becomes to move to thereactor 11 through the main pipe 15. In this way, the inside of theadsorber 12 is not abnotinally over-pressurized. Accordingly, similarlyto the aforementioned second embodiment, since it is not needed to makethe rigidity of the adsorber 12 higher than needed, a physicalconstitution and a weight of the adsorber 12 can be suppressed fromincreasing.

Notably, in the present embodiment, while control is performed so as toopen the solenoid valve 16 when the pressure in the adsorber 12 is notless than the setting pressure, not specially limited to this, apressure sensor that detects the pressure in the reactor 11 may also beprovided and control may also be performed so as to open the solenoidvalve 16 when the pressure in the reactor 11 becomes not less than thesetting pressure.

Moreover, also in the present embodiment, the relief valve 30 in theaforementioned third embodiment may also be separately included.

As above, some preferred embodiments of the chemical thermal storagedevice according to the present invention have been described.Nevertheless, the present invention is not limited to the aforementionedembodiments. For example, in the aforementioned first to fifthembodiments, while any one of the safety valve 18, the safety valve 21and the check valve 42 each of which is the first valve whichmechanically opens when the pressure in the reactor 11 reaches the firstvalve-opening setting pressure is provided, not providing the firstvalve which opens when the pressure in the reactor 11 reaches the firstvalve-opening setting pressure, a configuration to provide the secondvalve which opens when the pressure in the adsorber 12 reaches thesecond valve-opening setting pressure may also be employed.

Moreover, in the aforementioned second, third and fifth embodiments,while the second valve-opening setting pressure of the second valve isset to be higher than the first valve-opening setting pressure of thefirst valve, not specially limited to that mode, the secondvalve-opening setting pressure of the second valve may also be set equalto the first valve-opening setting pressure of the first valve.

Moreover, in the aforementioned embodiments, while NH_(;) is used as thegaseous reaction medium which undergoes chemical reaction with thethermal storage material 13 in the reactor 11, not specially limited toNH₃ as the reaction medium, CO₂ or the like may also be used. When CO₂is used as the reaction medium, examples of the thermal storage material13 which undergoes chemical reaction with CO₂ include MgO, CaO, BaO,Ca(OH)₂, Mg(OH)₂, Fe(OH)₂, Fe(OH)₃, FeO, Fe₂O₃ and Fe₃O₄.

Furthermore, in the aforementioned embodiments, while the reactor 11 isdisposed around the heat exchanger 4, not specially limited to this, theplace where the reactor 11 is disposed may also be, for example, theinside of the heat exchanger 4.

Moreover, in the aforementioned embodiments, while the adsorber 12contains the adsorption material 14 which performs physical adsorptionof NH₃, not specially limited to this, the adsorber 12 may also containan adsorption material that performs chemical adsorption of NH₃.

Furthermore, while the aforementioned embodiments heat the heatexchanger 4 provided in the exhaust system of the diesel engine 2, thepresent invention can also be applied to one which heats another portion(oxidation catalyst 5 or the like) provided in the exhaust system of thediesel engine 2. Moreover, the present invention can also be applied toone which heats a catalyst or the like provided in an exhaust system ofa gasoline engine, or one which heats a heating object other than theexhaust system of the engine.

REFERENCE SIGNS LIST

4 . . . Heat exchanger (heating object), 3 . . . Exhaust passage(exhaust system), 10 . . . Chemical thermal storage device, 11 . . .Reactor, 12 . . . Adsorber, 13 . . . Thermal storage material, 14 . . .Adsorption material, 16 . . . Solenoid valve (opening and closingvalve), 17 . . . Bypass pipe (bypass passage), 18 . . . Safety valve(first valve; communication part), 21 . . . Safety valve (first valve;communication part), 22 . . . Safety valve (second valve; communicationpart), 30 . . . Relief valve, 41 . . . Solenoid valve (opening andclosing valve), 42 . . . Check valve (first valve; communication part),45 . . . Safety valve (second valve; communication part), 46 . . .Bypass pipe (bypass passage), 50 . . . Pressure sensor (detector;communication part), 51 . . . Controller (detector; communication part).

1. A chemical thermal storage device which heats a heating object, thedevice comprising: a reactor having a thermal storage material thatgenerates heat upon chemical reaction with a gaseous reaction medium; anadsorber having an adsorption material that adsorbs the reaction medium;an opening and closing valve that is provided between the reactor andthe adsorber, and opens and closes a flow channel between the reactorand the adsorber; and communication part that causes the reactor and theadsorber to communicate with each other when an internal pressure of atleast one of the reactor and the adsorber becomes not less than apredetermined value.
 2. The chemical thermal storage device according toclaim 1, wherein the communication part is provided between the reactorand the adsorber, and has at least one of a first valve that opens whenthe internal pressure of the reactor reaches a first valve-openingsetting pressure that is preset and a second valve that opens when theinternal pressure of the adsorber reaches a second valve-opening settingpressure that is preset.
 3. The chemical thermal storage deviceaccording to claim 2, wherein the first valve includes a check valvefunction to shut off a flow of the reaction medium from the adsorber tothe reactor, and the second valve includes a check valve function toshut off a flow of the reaction medium from the reactor to the adsorber.4. The chemical thermal storage device according to claim 2, wherein thefirst valve and the second valve are provided between the reactor andthe adsorber, and the second valve-opening setting pressure is largerthan the first valve-opening setting pressure.
 5. The chemical thermalstorage device according to claim 2, wherein any one of the first valveand the second valve constitutes one unit along with the opening andclosing valve.
 6. The chemical thermal storage device according to claim2, wherein the communication part further has a bypass passage providedin parallel to the opening and closing valve, and at least one of thefirst valve and the second valve is provided on the bypass passage. 7.The chemical thermal storage device according to claim 1, wherein thecommunication part has detector that detects the internal pressure of atleast one of the reactor and the adsorber, and controller that performscontrol so as to open the opening and closing valve when it is detectedby the detector that the internal pressure of at least one of thereactor and the adsorber is not less than the predetermined value. 8.The chemical thermal storage device according to claim 1, furthercomprising a relief valve that opens when the internal pressure of atleast one of the reactor and the adsorber reaches a preset reliefsetting value.
 9. The chemical thermal storage device according to claim8, wherein the heating object is provided in an exhaust system of anengine, and the relief valve is provided between the exhaust system andat least one of the reactor and the adsorber.